Fabrication of a printer drum



" Nov. 24, 197 0 F. ca. DEDEK FABRICATION OF A PRINTER DRUM Filed Nov.15, 1967 INVENTOR.

A T TOR/VB Y.

FRANK e. DEDEK.

United States Patent Office 3,542,620 FABRICATION OF A PRINTER DRUMFrank G. Dedek, Westlantl, Mich., assignor to Burroughs Corporation,Detroit, Mich., a corporation of Michigan Filed Nov. 15, 1967, Ser. No.683,188 Int. Cl. B32b 31/00 US. Cl. 156-293 1 Claim ABSTRACT OF THEDISCLOSURE A method of fabricating a printing drum comprising a shaftand a plurality of type-carrying discs axially mounted thereon. Eachdisc carries a plurality of type characters spaced around its periphery.Each disc is bonded to the shaft by a layer of bonding material, such asan epoxy, between the disc and the shaft. Each disc is further bonded byan adhesive film placed between adjacent discs. Both the bondingmaterial and the adhesive film are then cured. Before curing,corresponding type characters on each disc are aligned to every otherdisc. Alignment is performed at the type characters to assure accuracy.

BACKGROUND OF THE INVENTION Field of invention The invention relatesgenerally to printing drums particularly and to a method of fabricatinga plurality of type discs and shaft into a printing drum unit.

Description of prior art At present, the method of fabricating printingdrums includes the keying of a number of type carrying discs to a shaft.In fabricating the key and cutting the keyway for a printing drum, thecost is exorbitant because a high degree of accuracy in machining mustbe maintained if the type are to align. The angular location of a keywayin the center of a printing disc with the type character on theperiphery of the disc is extremely difficult to maintain and result infrequent scraping of the parts. A tolerance of .0005 inch in the keywaylocation generally results in a character tolerance of from two to fivetimes that amount, depending on the size of the disc.

SUMMARY OF THE INVENTION This invention resides in bonding togetherseveral typecarrying discs on a shaft which together comprise a printingdrum. This method of fabricating a printing drum provides for accuratealignment of each type character in rows parallel to the shaft byaligning at the periphery of the disc instead of by key and keywayconnections at the periphery of the shaft.

It is therefore, a principal object of this invention to eliminate keysand keyways for locating printing discs along a mounting shaft.

A further object of this invention to reduce the cost of fabricatingprinting drum assemblies by eliminating the need for close tolerances onthe mounting surfaces of the several discs comprising a printing drumassembly.

DESCRIPTION OF FIGURES The invention will best be understood byreference to the following detailed description taken in connection withthe accompanying drawings, in which:

FIG. 1 is a end view of a printing drum showing the type aligning bailin position;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1.

DETAILED DESCRIPTION Referring to the drawings by characters ofreference, there is shown in FIG. 1 a printing drum unit comprising ashaft 11 and a plurality of centrally apertured type discs 13 positionedon the shaft. A pair of clamps 15 and 17 are indicated on either side ofthe type discs 13 holding the apparatus together. Also, there is shownone form of an aligning bail 19 for aligning the type of the discs 13 inrows, the bail being supported on the shaft as shown.

The clamps 15 and 17, shown in FIG. 2, are slideably mounted on shaft 11and are secured by any suitable means, such as set screws 21 and 23. Thepurpose of the clamps is to hold the type discs together in a drum-likefashion until the fabricating process has been completed. Mounted toeach clamp 15 and 17 are a pair of arms 25 and 27 which extend away fromthe shaft 11 to support the aligning bail 19. The outboard end 28 of thearm 25 is bifurcated to form a locating channel 31 for the aligning arm19. The aligning arm 19 is rotatably mounted on the hinge pin 29 whichis securely located in the arms 33 and 35. The depth A of the channel 31is sufiicient to allow the aligning bail to freely pivot about the hingepin. In a similar manner, the outboard end 37 of arm 27 is alsobifurcated to locate the aligning bail 19 by a pin 38.

In FIG. 1, the aligning bail is shown as having an U shapedcross-section which locates on either side of a type face 39. Such atype face may represent the letter O which generally has parallel sides.As shown in FIG. 1, the aligning bail locates along the top and bottomparallel sides of the letter.

Each type disc 13 is cylindrical in shape having broad parallel sidesand having a plurality of type characters around its periphery. Thewidth of the type disc assures that when two or more discs are in anabutting relationship, the distance from character to character on thetype discs is within the requirement of the printing drum. The broadsides of each type disc have an undercut area or recess 18 between themounting hole 41 and the periphery. The mounting hole 41 is concentricwith the periphery of the disc. A countersink is formed at each end ofthe mounting hole. Thus, the disc 13 is shaped like a wheel having awide rim and a wide center hub, both parallel to the axis of the discwith a reduced web interconnecting the two.

With the previous described clamping and aligning apparatus, thefollowing steps complete the method of fabrication. First, the clamp 15and the arm 25 are securely mounted at one end of the shaft 11. A typedisc 13 is located on the shaft by means of its mounting hole 41. Thefirst type disc is placed adjacent to and in contact with the clamp 15.A small amount of liquid bonding material 40, such as a thermallycurable liquid epoxy, is applied to the mounting hole 41 and theperiphery of the shaft 11 through the countersink. Next, one or moresheets of a suitable thermosetting adhesive film 42 is located on theshaft 11 and in the recess 18 of the type disc 13. The reason for usingan adhesive film in this application as opposed to a liquid form ofbonding material, is to prevent the bonding material from flowingoutward and adhering to the face of the type characters. A second disc13A is then located on the shaft and is positioned against the innersurface 43 of the preceding type disc 13. A small amount of epoxy isthen added to the mounting hole 41A and along the shaft 11. Then asecond piece of adhesive film 42A is mounted on the shaft and againstthe type disc 13A. This process is continued until the desired number oftype discs are assembled on the shaft. After assembling the last typedisc, the clamp 17 is then located on the shaft to contain the assembledtype discs in an abutting relationship 3 to each other to maintain apressure contact between each disc. The aligning bail 19 is then broughtinto place along the selected type character 39, as shown in FIG. 2. Thepin 38 is placed in the arm 27 and through the aligning bail securing itinto position.

The step of aligning is accomplished at the type faces when all of thetype discs are mounted on the shaft 11. There is no need to rely uponthe quality of individual machining of the mounting holes in each typedisc to have the type faces in proper alignment. The adhesive film 42between each disc securely bonds each disc to each other disc, and theliquid epoxy 40' in the mounting holes 41 securely bonds the discs 13 tothe shaft.

The assembled unit is then cured. Curing may take place at an elevatedtemperature, such as 330 F., for a time period of 30 minutes if thepreviously mentioned bonding materials are used. The time andtemperature of curing is solely dependent upon the type and kind ofbonding material used. After the step of curing, the aligning bail 19,the clamps 15 and 17 including the arms 25 and 27 are removed from theapparatus and the printing drum is completed.

While we have shown one particular apparatus, the aligning bail, foraligning the several type discs, there are many means which are equallysatisfactory. One such means is to assemble the several type discs Withthe use of a magnifying projector and visually locate adjacent typecharacters. In order to do this, the bonding material selected should besomewhat tacky so as to hold each disc while the drum is being assembledand aligned.

Another way of aligning the type discs is to use a bail having animpression of a character in the desired axial spaced relationship ofthe finished drum. The character on each type disc may be accuratelylocated in the impression and the several type discs accurately alignedone to the other.

4 It will be apparent that many changes and modifications of the severalfeatures described herein may be made without departing from the spiritand scope of the invention. It is, therefore, apparent that theforegoing description is by way of illustration of the invention ratherthan limitation of the invention.

What is claimed is: 1. A method of fabricating a printing drumcomprising the steps of:

forming like type characters on the periphery of each of a plurality ofannular discs, placing the type discs concentrically on a shaft,applying a predetermined amount of a thermally curable liquid adhesivebetween the periphery of the shaft and the inner periphery of eachannular disc, placing a predetermined number of annular sheets ofthermosetting adhesive film respectively between the adjacent sides ofthe discs, rotating the discs to InOVe the characters into abuttingrelation with a straight edge parallel to the axes of the disc while theliquid adhesive and adhesive film is uncured, and then thermally curingboth adhesives to form a bond between the periphery of the shaft and theinner periphery of each disc and between each adjacent disc.

References Cited UNITED STATES PATENTS 1,576,726 3/1926 Davis 156-294 X2,423,869 7/1947 Blessing 156-60 3,128,693 4/1964 Thiemann 101-933,184,355 5/1965 Brown 156-294 X 3,222,234 12/1965 De Jean et a1 264-262REUBEN EPSTEIN, Primary Examiner US. Cl. X.R. 29-464

